High flow tpo composition with excellent low temperature impact

ABSTRACT

The present invention is directed to a heterophasic propylene copolymer (HECO), a polyolefin composition (PO) comprising the heterophasic propylene copolymer (HECO), an automotive article comprising the heterophasic propylene copolymer (HECO) and/or the polyolefin composition (PO) and a process for the preparation of the polyolefin composition (PO) as well as the use of the heterophasic propylene copolymer (HECO) for improving the mechanical properties of a polyolefin composition (PO).

The present invention is directed to a heterophasic propylene copolymer(HECO), a polyolefin composition (PO) comprising the heterophasicpropylene copolymer (HECO), an automotive article comprising theheterophasic propylene copolymer (HECO) and/or the polyolefincomposition (PO) and a process for the preparation of the polyolefincomposition (PO) as well as the use of the heterophasic propylenecopolymer (HECO) for improving the mechanical properties of a polyolefincomposition (PO).

Polypropylene is the material of choice in many applications as it canbe tailored to specific purposes needed. For instance, heterophasicpropylene copolymers (HECOs), are widely used in the automobile industrye.g. in bumper, dashboard, side trim panel, rocker panel and fenderapplications. Heterophasic polypropylenes contain a polypropylene matrixin which an amorphous phase is dispersed.

The injection moulding of these large automotive parts requires polymerswith a low viscosity (for easy filling of the mould) but still balancedmechanical performance, particularly well-balanced stiffness andtoughness. Increasing the flowability usually goes along with a decreasein the molecular weight of the polymer chains. A lower molecular weightdoes not only result in a lower viscosity of the polymer but also altersits mechanical properties, e.g. lowers the toughness. Hence thecombination of high flowability and excellent mechanics, i.e.well-balanced stiffness and toughness, is not trivial to achieve.

Many attempts have been made in the art to provide polyolefincompositions comprising heterophasic propylene copolymers having therequired good flowability combined with excellent balance in stiffnessand toughness. For instance, WO 2013150057 A1 discloses thermoplasticpolyolefin compositions comprising a matrix phase and a dispersed phase.The intrinsic viscosity of the dispersed phase is rather low andconsequently also the toughness of the polyolefin composition is low. WO2005113672 A1 discloses polyolefin compositions having acceptablestiffness and toughness, but particularly for those embodiments withrather good balance in stiffness and toughness, the flowability isinsufficient.

Thus, the object of the present invention is to provide a material whichprovides a combination of good flowability with an excellentstiffness/toughness balance below ambient temperature.

The finding of the present invention is to provide a heterophasicpropylene copolymer (HECO) comprising a propylene homopolymer (HPP) andan elastomeric propylene-ethylene copolymer (E) with definedcharacteristics.

Accordingly the present invention is directed to heterophasic propylenecopolymer (HECO) comprising

-   a) a propylene homopolymer (HPP) having a melt flow rate MFR₂ (230°    C.) measured according to ISO 1133 in the range of 200 to 350 g/10    min, and-   b) an elastomeric propylene-ethylene copolymer (E),-   wherein the heterophasic propylene copolymer (HECO)-   (i) has a melt flow rate MFR₂ (230° C.) measured according to ISO    1133 in the range of 15 to 35 g/10 min,-   (ii) comprises a xylene cold soluble (XCS) fraction in an amount    from 34 to 40 wt.-%, based on the total weight of the heterophasic    propylene copolymer (HECO),-   wherein further the xylene cold soluble (XCS) fraction of the    heterophasic propylene copolymer (HECO) has-   (iii) an intrinsic viscosity (IV) in the range of 2.8 to 3.8 dl/g,    and-   (iv) an ethylene content (EC) of 25 to 35 wt.-%.

According to one embodiment of the heterophasic propylene copolymer(HECO), the propylene homopolymer (HPP) is unimodal with respect to themelt flow rate MFR₂ (230° C.) measured according to ISO 1133 and/or hasa xylene cold soluble (XCS) content no higher than 5 wt.-%.

According to another embodiment of the heterophasic propylene copolymer(HECO), the heterophasic propylene copolymer (HECO) has an ethylenecontent (EC-HECO) of 8 to 17 wt.-%, based on the total weight of theheterophasic propylene copolymer (HECO).

According to yet another embodiment of the heterophasic propylenecopolymer (HECO), the xylene cold soluble (XCS) fraction is unimodalwith respect to the ethylene content (EC) and/or unimodal with respectto the molecular weight distribution (MWD).

According to one embodiment of the heterophasic propylene copolymer(HECO), the weight ratio of heterophasic propylene copolymer (HECO) tothe polypropylene homopolymer (HPP) [HECO/HPP] is from 3.0:1.0 to1.0:1.0.

According to another embodiment of the heterophasic propylene copolymer(HECO), the heterophasic propylene copolymer (HECO) is α-nucleated, i.e.comprises a α-nucleating agent.

According to another aspect of the present invention, a polyolefincomposition (PO) is provided. The polyolefin composition (PO) comprises≥95 wt.-%, based on the total weight of the composition, of theheterophasic propylene copolymer (HECO), as defined herein.

According to one embodiment of the polyolefin composition (PO), thecomposition comprises an inorganic filler (F), preferably the filler isselected from the group consisting of talc, wollastonite, mica, chalkand mixtures thereof.

According to another embodiment of the polyolefin composition (PO), thecomposition has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, and-   ii) a tensile modulus of ≥750 MPa, and/or-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², and/or-   iv) a Charpy Notched impact strength at −20° C. of ≥8 kJ/m².

According to yet another embodiment of the polyolefin composition (PO),the composition has

-   i) a tensile modulus in the range of 750 to 1050 MPa, and/or-   ii) a Charpy Notched impact strength at 23° C. in the range of 30 to    60 kJ/m², and/or-   iii) a Charpy Notched impact strength at −20° C. in the range of 8    to 14 kJ/m².

The present invention also relates to an automotive article comprisingthe heterophasic propylene copolymer (HECO), as defined herein, and/orthe polyolefin composition (PO), as defined herein.

It is preferred that the automotive article is an exterior or interiorautomotive article selected from bumpers, body panels, rocker panels,side trim panels, interior trims, step assists, spoilers, fenders anddash boards.

A further aspect of the present invention relates to process for thepreparation of the polyolefin composition (PO), as defined herein, byextruding the heterophasic propylene copolymer (HECO) and the optionalinorganic filler (F) in an extruder.

According to one embodiment of the process, the heterophasic propylenecopolymer (HECO) is obtained by producing the propylene homopolymer(HPP) in at least one reactor, transferring said propylene homopolymer(HPP) in at least one subsequent reactor, where in the presence of thepropylene homopolymer (HPP) the elastomeric propylene-ethylene copolymer(E) is produced.

A further aspect of the present invention is the use of the heterophasicpropylene copolymer (HECO), as defined herein, for improving themechanical properties of a polyolefin composition (PO), wherein theimprovement is achieved when the composition has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, and-   ii) a tensile modulus of ≥750 MPa, and/or-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², and/or-   iv) a Charpy Notched impact strength at −20° C. of ≥8 kJ/m².

In the following the invention will be described in more detail.

Heterophasic Propylene Copolymer (HECO)

The heterophasic propylene copolymer (HECO) of the present inventioncomprises

-   a) a propylene homopolymer (HPP) having a melt flow rate MFR₂ (230°    C.) measured according to ISO 1133 in the range of 200 to 350 g/10    min, and-   b) an elastomeric propylene-ethylene copolymer (E),-   wherein the heterophasic propylene copolymer (HECO)-   (i) has a melt flow rate MFR₂ (230° C.) measured according to ISO    1133 in the range of 15 to 35 g/10 min,-   (ii) comprises a xylene cold soluble (XCS) fraction in an amount    from 34 to 40 wt.-%, based on the total weight of the heterophasic    propylene copolymer (HECO),-   wherein further the xylene cold soluble (XCS) fraction of the    heterophasic propylene copolymer (HECO) has-   (iii) an intrinsic viscosity (IV) in the range of 2.8 to 3.8 dl/g,    and-   (iv) an ethylene content (EC) of 25 to 35 wt.-% based on the total    weight of the xylene cold soluble (XCS) fraction of the heterophasic    propylene copolymer (HECO).

It is apparent from the wording used for the different polymers (HECO,HPP and E) according to the present invention that they must(chemically) differ from each other. The expression “heterophasic”indicates that the matrix, i.e. the propylene homopolymer (HPP),contains (finely) dispersed inclusions being not part of the matrix andsaid inclusions contain the elastomeric propylene-ethylene copolymer(E). The term “inclusion” according to this invention shall preferablyindicate that the matrix, i.e. the propylene homopolymer (HPP), and theinclusion, i.e. the elastomeric propylene-ethylene copolymer (E) formdifferent phases within the heterophasic propylene copolymer (HECO),said inclusions are for instance visible by high resolution microscopy,like electron microscopy or scanning force microscopy. The finalpolyolefin composition (PO) comprising the matrix, i.e. the propylenehomopolymer (HPP), and the elastomeric propylene-ethylene copolymer (E)as part of the heterophasic propylene copolymer (HECO) is probably of acomplex structure.

Thus, the heterophasic propylene copolymer (HECO) according to thisinvention comprises

-   a) a propylene homopolymer (HPP) as matrix (M), and-   b) an elastomeric propylene-ethylene copolymer (E) comprising,    preferably consisting of, units derived from propylene and ethylene.

Preferably, the propylene content (PC-HECO) in the heterophasicpropylene copolymer (HECO) is 83 to 92 wt.-%, more preferably 83 to 87wt.-%, based on the total weight of the heterophasic propylene copolymer(HECO), more preferably based on the amount of the polymer components ofthe heterophasic propylene copolymer (HECO), yet more preferably basedon the amount of the matrix (M), i.e. the propylene homopolymer (HPP),and the elastomeric propylene-ethylene copolymer (E) together. Theremaining part constitutes the comonomers, preferably ethylene.

Accordingly, the comonomer content, preferably the ethylene content(EC-HECO), in the heterophasic propylene copolymer (HECO) is preferably8 to 17 wt.-%, more preferably 13 to 17 wt.-%, based on the total weightof the heterophasic propylene copolymer (HECO), more preferably based onthe amount of the polymer components of the heterophasic propylenecopolymer (HECO), yet more preferably based on the amount of the matrix(M), i.e. the propylene homopolymer (HPP), and the elastomericpropylene-ethylene copolymer (E) together.

It is preferred that the propylene homopolymer (HPP) content in theheterophasic propylene copolymer (HECO) is in the range of 60 to 66wt.-%, more preferably in the range of 62 to 66 wt.-%, based on thetotal weight of the heterophasic propylene copolymer (HECO).

On the other hand the elastomeric propylene-ethylene copolymer (E)content in the heterophasic propylene copolymer (HECO) is preferably inthe range of 34 to 40 wt.-%, more preferably in the range of 34 to 38wt.-%, based on the total weight of the heterophasic propylene copolymer(HECO).

It is preferred that the propylene homopolymer (HPP) is present in aspecific weight ratio compared to the heterophasic propylene copolymer(HECO).

For example, the weight ratio of the heterophasic propylene copolymer(HECO) to the polypropylene homopolymer (HPP) [HECO/HPP] is from 3.0:1.0to 1.0:1.0. Preferably, the weight ratio of the heterophasic propylenecopolymer (HECO) to the polypropylene homopolymer (HPP) [HECO/HPP] isfrom 2.5:1.0 to 1.0:1.0, more preferably from 2.0:1.0 to 1.1:1.0, andmost preferably from 1.8:1.0 to 1.1:1.0.

It is one requirement of the present invention that the heterophasicpropylene copolymer (HECO) has a melt flow rate MFR₂ (230° C.) measuredaccording to ISO 1133 in the range of 15 to 35 g/10 min, preferably inthe range of 18 to 30 g/10 min.

The polypropylene matrix (M) of the heterophasic propylene copolymer(HECO) is a propylene homopolymer (HPP).

The expression propylene homopolymer (HPP) used in the instant inventionrelates to a polypropylene that consists substantially, i.e. of morethan 99.7 wt.-%, still more preferably of at least 99.8 wt.-%, ofpropylene units. In a preferred embodiment only propylene units in thepropylene homopolymer (HPP) are detectable.

Accordingly the comonomer content of the polypropylene matrix (M), i.e.of the propylene homopolymer (HPP), is preferably equal or below 0.3wt.-%, like not more than 0.2 wt.-%, e.g. non detectable.

It is a further requirement that the polypropylene matrix (M), i.e. ofthe propylene homopolymer (HPP), of the heterophasic propylene copolymer(HECO) has a relatively high melt flow MFR₂ (230° C.). Accordingly, itis preferred that the propylene homopolymer (HPP) of the heterophasicpropylene copolymer (HECO) has a melt flow rate MFR₂ (230° C.) measuredaccording to ISO 1133 in the range of 200 to 350 g/10 min, morepreferably 230 to 350 g/10 min, still more preferably 230 to 320 g/10min.

It is preferred that the propylene homopolymer (HPP) of the heterophasicpropylene copolymer (HECO) is unimodal with respect to the melt flowrate MFR₂ (230° C.) measured according to ISO 1133.

It is preferred that the propylene homopolymer (HPP) has a specific meltflow rate MFR₂ (230° C.) compared to the heterophasic propylenecopolymer (HECO).

For example, the melt flow rate MFR₂ (230° C.) of the polypropylenehomopolymer (HPP) [HECO/HPP], measured according to ISO 1133, to themelt flow rate MFR₂ (230° C.) of the heterophasic propylene copolymer(HECO), measured according to ISO 1133, [MFR₂ (HPP)/MFR₂ (HECO)] is from20.0:1.0 to 5.0:1.0. Preferably, the melt flow rate MFR₂ (230° C.) ofthe polypropylene homopolymer (HPP) [HECO/HPP], measured according toISO 1133, to the melt flow rate MFR₂ (230° C.) of the heterophasicpropylene copolymer (HECO), measured according to ISO 1133, [MFR₂(HPP)/MFR₂ (HECO)] is from 18.0:1.0 to 5.0:1.0, more preferably from16.0:1.0 to 7:1.0, and most preferably from 15.0:1.0 to 8.0:1.0.

Preferably, the xylene cold soluble content of the matrix (M), i.e. thepropylene homopolymer (HPP), of the heterophasic propylene copolymer(HECO) is no higher than 5 wt.-%, more preferable no higher than 4.5wt.-%, still more preferably no higher than 3.5 wt.-%, based on thetotal weight of the propylene homopolymer (HPP).

Additionally or alternatively, the comonomer content, preferablyethylene content, of the matrix (M), i.e. the propylene homopolymer(HPP), of the heterophasic propylene copolymer (HECO) is no higher than2 wt.-%, more preferable no higher than 1.5 wt.-%, still more preferablyno higher than 1 wt.-%, based on the total weight of the propylenehomopolymer (HPP). Preferably, the comonomer content, preferablyethylene content, of the matrix (M), i.e. the propylene homopolymer(HPP), of the heterophasic propylene copolymer (HECO) is no higher than0.5 wt.-%, more preferable no higher than 0.3 wt.-%, still morepreferably no higher than 0.1 wt.-%, based on the total weight of thepropylene homopolymer (HPP).

In one embodiment, the propylene homopolymer (HPP) has a molecularweight (Mw) preferably between 100,000-400,000 such as from100,000-250,000.

Additionally or alternatively, the propylene homopolymer (HPP) has amolecular weight distribution (MWD) preferably between 3-9 such as from4-8.

One further essential component of the heterophasic propylene copolymer(HECO) is the elastomeric propylene-ethylene copolymer (E).

The elastomeric propylene-ethylene copolymer (E) comprises, preferablyconsists of, units derivable from (i) propylene and (ii) ethylene.

In the present invention the content of units derivable from propylene(PC) in the elastomeric propylene-ethylene copolymer (E) is preferablyin the range from 65 to 75 wt.-%, more preferably 65 to 73 wt.-%, evenmore preferably 66 to 71 wt.-% and most preferably 66 to 70 wt.-%, basedon the total weight of the elastomeric propylene-ethylene copolymer (E).

Thus, the elastomeric propylene-ethylene copolymer (E) preferablycomprises units derivable from ethylene (EC) from 25 to 35 wt.-%, morepreferably from 27 to 35 wt.-%, even more preferably from 29 to 34 wt.-%and most preferably from 30 to 34 wt.-%, based on the total weight ofthe elastomeric propylene-ethylene copolymer (E). Preferably, theelastomeric propylene-ethylene copolymer (E) is an ethylene propylenenon-conjugated diene monomer polymer (EPDM1) or an ethylene propylenerubber (EPR1), the latter especially preferred, with a propylene and/orethylene content as defined in this and the previous paragraph.

It is preferred that the elastomeric propylene-ethylene copolymer (E) ofthe heterophasic propylene copolymer (HECO) is unimodal with respect tothe melt flow rate MFR₂ (230° C.) measured according to ISO 1133.

In one embodiment, the elastomeric propylene-ethylene copolymer (E)preferably has an unimodal molecular weight distribution. Preferably,the elastomeric propylene-ethylene copolymer (E) has a molecular weight(Mw) preferably between 150,000-700,000 such as from 250,000-650,000.

Additionally or alternatively, the elastomeric propylene-ethylenecopolymer (E) has a molecular weight distribution (MWD) preferablybetween 3.5-8 such as from 3.5-7.

In one embodiment, the heterophasic propylene copolymer (HECO) has a Mw(XCS) to Mw (XCU) between 1.5-3.5 such as from 2-3.

The heterophasic propylene copolymer (HECO) comprises a xylene coldsoluble (XCS) fraction.

It is one requirement of the present invention that the heterophasicpropylene copolymer (HECO) comprises a xylene cold soluble (XCS)fraction in an amount from 34 to 40 wt.-%, based on the total weight ofthe heterophasic propylene copolymer (HECO). For example, theheterophasic propylene copolymer (HECO) comprises the xylene coldsoluble (XCS) fraction in an amount from 34 to 38 wt.-%, based on thetotal weight of the heterophasic propylene copolymer (HECO).

It is a further requirement of the present invention that the xylenecold soluble (XCS) fraction of the heterophasic propylene copolymer(HECO) comprises units derivable from ethylene (EC) from 25 to 35 wt.-%,more preferably from 27 to 35 wt.-%, even more preferably from 29 to 34wt.-% and most preferably from 30 to 34 wt.-%, based on the total weightof the xylene cold soluble (XCS) fraction of the heterophasic propylenecopolymer (HECO).

It is preferred that the xylene cold soluble (XCS) fraction of theheterophasic propylene copolymer (HECO) is unimodal with respect to theethylene content (EC).

Additionally or alternatively, the propylene detectable in the xylenecold soluble (XCS) fraction preferably ranges from 65 to 75 wt.-%, morepreferably 65 to 73 wt.-%, even more preferably 66 to 71 wt.-% and mostpreferably 66 to 70 wt.-%.

In one embodiment of the present invention, the intrinsic viscosity (IV)of the xylene cold soluble (XCS) fraction of the heterophasic propylenecopolymer (HECO) is rather high. Rather high values of intrinsicviscosity (IV) improve the toughness. Accordingly, it is appreciatedthat the intrinsic viscosity of the xylene cold soluble (XCS) fractionof the heterophasic propylene copolymer (HECO) is above 2.8 dl/g. On theother hand the intrinsic viscosity (IV) should be not too high otherwisethe flowability is decreased. Thus, it is one further requirement of thepresent invention that the intrinsic viscosity of the xylene coldsoluble (XCS) fraction of the heterophasic propylene copolymer (HECO) isin the range of 2.8 to 3.8 dl/g.

It is preferred that the xylene cold soluble (XCS) fraction of theheterophasic propylene copolymer (HECO) is unimodal with respect to themelt flow rate MFR₂ (230° C.) measured according to ISO 1133.

In one embodiment, the xylene cold soluble (XCS) fraction of theheterophasic propylene copolymer (HECO) preferably has an unimodalmolecular weight distribution. Preferably, the xylene cold soluble (XCS)fraction of the heterophasic propylene copolymer (HECO) has a molecularweight (Mw) preferably between 150,000-700,000 such as from250,000-650,000.

Additionally or alternatively, the xylene cold soluble (XCS) fraction ofthe heterophasic propylene copolymer (HECO) has a molecular weightdistribution (MWD) preferably between 3.5-8 such as from 3.5-7.

Preferably, it is desired that the heterophasic propylene copolymer(HECO) shows good toughness. Accordingly, it is appreciated that theheterophasic propylene copolymer (HECO) has a Charpy notched impactstrength at +23° C. of ≥30 kJ/m², more preferably in the range of 30 to60 kJ/m², still more preferably in the range of 35 to 60 kJ/m² and mostpreferably in the range of 40 to 60 kJ/m².

Additionally or alternatively, the heterophasic propylene copolymer(HECO) has a Charpy notched impact strength at −20° C. of ≥8 kJ/m², morepreferably in the range of 8 to 14 kJ/m², still more preferably in therange of 9 to 14 kJ/m² and most preferably in the range of 9 to 13kJ/m².

Additionally or alternatively, the heterophasic propylene copolymer(HECO) should have good tensile modulus. It is preferred that thetensile modulus of the heterophasic propylene copolymer (HECO) is ≥750MPa, more preferably in the range of 750 to 1050 MPa, even morepreferably of 800 to 1000 MPa, still more preferably in the range of 800to 980 MPa and most preferably in the range of 800 to 950 MPa.

Thus, the heterophasic propylene copolymer (HECO) preferably has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, preferably in the range of 18 to 30    g/10 min, and-   ii) a tensile modulus of ≥750 MPa, more preferably in the range of    750 to 1050 MPa, even more preferably of 800 to 1000 MPa, still more    preferably in the range of 800 to 980 MPa and most preferably in the    range of 800 to 950 MPa, and/or-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², more    preferably in the range of 30 to 60 kJ/m², still more preferably in    the range of 35 to 60 kJ/m² and most preferably in the range of 40    to 60 kJ/m², and/or-   iv) a Charpy notched impact strength at −20° C. of ≥8 kJ/m², more    preferably in the range of 8 to 14 kJ/m², still more preferably in    the range of 9 to 14 kJ/m² and most preferably in the range of 9 to    13 kJ/m².

In one embodiment, the heterophasic propylene copolymer (HECO) has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, preferably in the range of 18 to 30    g/10 min, and-   ii) a tensile modulus of ≥750 MPa, more preferably in the range of    750 to 1050 MPa, even more preferably of 800 to 1000 MPa, still more    preferably in the range of 800 to 980 MPa and most preferably in the    range of 800 to 950 MPa, and-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², more    preferably in the range of 30 to 60 kJ/m², still more preferably in    the range of 35 to 60 kJ/m² and most preferably in the range of 40    to 60 kJ/m², or-   iv) a Charpy notched impact strength at −20° C. of ≥8 kJ/m², more    preferably in the range of 8 to 14 kJ/m², still more preferably in    the range of 9 to 14 kJ/m² and most preferably in the range of 9 to    13 kJ/m²

Alternatively, the heterophasic propylene copolymer (HECO) has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, preferably in the range of 18 to 30    g/10 min, and-   ii) a tensile modulus of ≥750 MPa, more preferably in the range of    750 to 1050 MPa, even more preferably of 800 to 1000 MPa, still more    preferably in the range of 800 to 980 MPa and most preferably in the    range of 800 to 950 MPa, or-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², more    preferably in the range of 30 to 60 kJ/m², still more preferably in    the range of 35 to 60 kJ/m² and most preferably in the range of 40    to 60 kJ/m², and-   iv) a Charpy notched impact strength at −20° C. of ≥8 kJ/m², more    preferably in the range of 8 to 14 kJ/m², still more preferably in    the range of 9 to 14 kJ/m² and most preferably in the range of 9 to    13 kJ/m².

Preferably, the heterophasic propylene copolymer (HECO) has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, preferably in the range of 18 to 30    g/10 min, and-   ii) a tensile modulus of ≥750 MPa, more preferably in the range of    750 to 1050 MPa, even more preferably of 800 to 1000 MPa, still more    preferably in the range of 800 to 980 MPa and most preferably in the    range of 800 to 950 MPa, and-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², more    preferably in the range of 30 to 60 kJ/m², still more preferably in    the range of 35 to 60 kJ/m² and most preferably in the range of 40    to 60 kJ/m², and-   iv) a Charpy notched impact strength at −20° C. in the range of 5 to    20 kJ/m², still more preferably in the range of 5 to 16 kJ/m² and    most preferably in the range of 6 to 13 kJ/m².

Preferably, the heterophasic propylene copolymer (HECO) is α-nucleated.Even more preferred the present invention is free of β-nucleatingagents. Accordingly, the α-nucleating agent is preferably selected fromthe group consisting of

-   (i) salts of monocarboxylic acids and polycarboxylic acids, e.g.    sodium benzoate or aluminum tert-butylbenzoate, and-   (ii) dibenzylidenesorbitol (e.g. 1,3:2,4 dibenzylidenesorbitol) and    C₁-C₈-alkyl-substituted dibenzylidenesorbitol derivatives, such as    methyldibenzylidenesorbitol, ethyldibenzylidenesorbitol or    dimethyldibenzylidenesorbitol (e.g. 1,3:2,4 di(methylbenzylidene)    sorbitol), or substituted nonitol-derivatives, such as    1,2,3,-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol,    and-   (iii) salts of diesters of phosphoric acid, e.g. sodium    2,2′-methylenebis (4, 6,-di-tert-butylphenyl) phosphate or    aluminium-hydroxy-bis[2,2′-methylene-bis(4,6-di-t-butylphenyl)phosphate],    and-   (iv) vinylcycloalkane polymer and vinylalkane polymer (as discussed    in more detail below), and-   (v) mixtures thereof.

Such additives are generally commercially available and are described,for example, in “Plastic Additives Handbook”, 5th edition, 2001 of HansZweifel, pages 871 to 873.

Preferably the heterophasic propylene copolymer (HECO) contains up to 5wt.-%, based on the total weight of the heterophasic propylene copolymer(HECO), of the α-nucleating agent. In a preferred embodiment, theheterophasic propylene copolymer (HECO) contains not more than 200 ppm,more preferably of 1 to 200 ppm, more preferably of 5 to 100 ppm of aα-nucleating agent, in particular selected from the group consisting ofdibenzylidenesorbitol (e.g. 1,3:2,4 dibenzylidene sorbitol),dibenzylidenesorbitol derivative, preferablydimethyldibenzylidenesorbitol (e.g. 1,3:2,4 di(methylbenzylidene)sorbitol), or substituted nonitol-derivatives, such as1,2,3,-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol,vinylcycloalkane polymer, vinylalkane polymer, and mixtures thereof.

It is especially preferred the heterophasic propylene copolymer (HECO)contains a vinylcycloalkane, like vinylcyclohexane (VCH), polymer and/orvinylalkane polymer. Preferably the vinylcycloalkane is vinylcyclohexane(VCH) polymer is introduced into the heterophasic propylene copolymer(HECO) by the BNT technology.

The instant heterophasic propylene copolymer (HECO) is preferablyobtained by a specific process. Accordingly the heterophasic propylenecopolymer (HECO) is preferably obtained by a sequential polymerizationprocess where in the first reactor (1^(st) R) and optionally in a secondreactor (2^(nd) R) the propylene homopolymer (HPP) is produced, whereasin the third reactor (3^(rd) R) and optionally in a fourth reactor(4^(th) R) the elastomeric propylene-ethylene copolymer (E) of theheterophasic propylene copolymer (HECO) is obtained.

In one embodiment, the heterophasic propylene copolymer (HECO) ispreferably obtained by a sequential polymerization process where in thefirst reactor (1^(st) R) the propylene homopolymer (HPP) is produced,whereas in the third reactor (3^(rd) R) the elastomericpropylene-ethylene copolymer (E) of the heterophasic propylene copolymer(HECO) is obtained.

Alternatively, the heterophasic propylene copolymer (HECO) is preferablyobtained by a sequential polymerization process where in the firstreactor (1^(st) R) and in a second reactor (2^(nd) R) the propylenehomopolymer (HPP) is produced, whereas in the third reactor (3^(rd) R)and the fourth reactor (4^(th) R) the elastomeric propylene-ethylenecopolymer (E) of the heterophasic propylene copolymer (HECO) isobtained.

The term “sequential polymerization process” indicates that theheterophasic propylene copolymer (HECO) is produced in at least tworeactors, preferably in three reactors or more, like four reactors,connected in series. Accordingly, the present process comprises at leasta first reactor (1^(st) R), an optional second reactor (2^(nd) R), athird reactor (3^(rd) R) and an optional fourth reactor (4^(th) R). Forexample, the present process comprises at least a first reactor (1^(st)R), a second reactor (2^(nd) R), a third reactor (3^(rd) R) and anoptional fourth reactor (4^(th) R), preferably at least a first reactor(1^(st) R), a second reactor (2^(nd) R), a third reactor (3^(rd) R) anda fourth reactor (4^(th) R). The term “polymerization reactor” shallindicate that the main polymerization takes place. Thus, in case theprocess consists of three or four polymerization reactors, thisdefinition does not exclude the option that the overall processcomprises for instance a pre-polymerization step in a pre-polymerizationreactor. The term “consist of” is only a closing formulation in view ofthe main polymerization reactors.

After the first reactor (1^(st) R) and optional second reactor (2^(nd)R) the matrix (M), i.e. the propylene homopolymer (HPP), of theheterophasic propylene copolymer (HECO), is obtained. This matrix (M) issubsequently transferred into the third reactor (3^(rd) R) and optionalfourth reactor (4^(th) R), preferably into the third reactor (3^(rd) R)and the fourth reactor (4^(th) R), in which the elastomericpropylene-ethylene copolymer (E) is produced and thus the heterophasicpropylene copolymer (HECO) of the instant invention is obtained.

Preferably the weight ratio between the matrix (M), i.e. the propylenehomopolymer (HPP), and the elastomeric propylene-ethylene copolymer (E)[(M)/(E)] is 85/15 to 55/45, more preferably 80/20 to 60/40.

The first reactor (1^(st) R) is preferably a slurry reactor (SR) and canbe any continuous or simple stirred batch tank reactor or loop reactoroperating in bulk or slurry. Bulk means a polymerization in a reactionmedium that comprises of at least 60% (w/w) monomer. According to thepresent invention the slurry reactor (SR) is preferably a (bulk) loopreactor (LR).

The optional second reactor (2^(nd) R), the third reactor (3^(rd) R) andthe optional fourth reactor (4^(th) R) are preferably gas phase reactors(GPR). Such gas phase reactors (GPR) can be any mechanically mixed orfluid bed reactors. Preferably the gas phase reactors (GPR) comprise amechanically agitated fluid bed reactor with gas velocities of at least0.2 msec. Thus it is appreciated that the gas phase reactor is afluidized bed type reactor preferably with a mechanical stirrer.

Thus, in a preferred embodiment the first reactor (1^(st) R) is a slurryreactor (SR), like loop reactor (LR), whereas the optional secondreactor (2^(nd) R), the third reactor (3^(rd) R) and the optional fourthreactor (4^(th) R) are gas phase reactors (GPR). Accordingly for theinstant process at least two, preferably two or three or fourpolymerization reactors, namely a slurry reactor (SR), like loop reactor(LR), an optionally first gas phase reactor (GPR-1), a second gas phasereactor (GPR-2) and optionally a third gas phase reactor (GPR-3)connected in series are used. If needed prior to the slurry reactor (SR)a pre-polymerization reactor is placed.

In one embodiment, the second reactor (2^(nd) R) can be a slurry reactor(SR). In this embodiment, the first reactor (1^(st) R) and the secondreactor (2^(nd) R) are slurry reactors (SR) and the third reactor(3^(rd) R) and the optional fourth reactor (4^(th) R) are gas phasereactors (GPR).

A preferred multistage process is a “loop-gas phase”-process, such asdeveloped by Borealis A/S, Denmark (known as BORSTAR® technology)described e.g. in patent literature, such as in EP 0 887 379, WO92/12182 WO 2004/000899, WO 2004/111095, WO 99/24478, WO 99/24479 or inWO 00/68315.

A further suitable slurry-gas phase process is the Spheripol® process ofBasell.

Preferably, in the instant process for producing the heterophasicpropylene copolymer (HECO), as defined above the conditions for thefirst reactor (1^(st) R), i.e. the slurry reactor (SR), like a loopreactor (LR), may be as follows:

-   -   the temperature is within the range of 40° C. to 110° C.,        preferably between 60° C. and 100° C., like 68 to 95° C.,    -   the pressure is within the range of 20 bar to 80 bar, preferably        between 35 bar to 70 bar,    -   hydrogen can be added for controlling the molar mass in a manner        known per se.

Subsequently, the reaction mixture from the first reactor (1^(st) R) maybe transferred to the optional second reactor (2^(nd) R), i.e. gas phasereactor (GPR-1), whereby the conditions are preferably as follows:

-   -   the temperature is within the range of 50° C. to 130° C.,        preferably between 60° C. and 100° C.,    -   the pressure is within the range of 5 bar to 50 bar, preferably        between 15 bar to 35 bar,    -   hydrogen can be added for controlling the molar mass in a manner        known per se.

If the first reactor (1^(st) R) and the second reactor (2^(nd) R) areslurry reactors, the conditions in the second reactor (2^(nd) R), i.e.the slurry reactor, are preferably similar to the first reactor (1^(st)R).

The condition in the third reactor (3^(rd) R) and optional fourthreactor (4^(th) R), preferably in the second gas phase reactor (GPR-2)and optionally in the third gas phase reactor (GPR-3), is similar to thesecond reactor (2^(nd) R). This preferably applies in case the secondreactor (2^(nd) R) is a gas phase reactor (GPR-1). In this embodiment,the conditions in the second reactor (2^(nd) R), i.e. the gas phasereactor (GPR-1), preferably differ from the conditions in the firstreactor (1^(st) R).

If the first reactor (1^(st) R) and the second reactor (2^(nd) R) areslurry reactors, the conditions in the third reactor (3^(rd) R) andoptional fourth reactor (4^(th) R) are preferably as follows:

-   -   the temperature is within the range of 50° C. to 130° C.,        preferably between 60° C. and 100° C.,    -   the pressure is within the range of 5 bar to 50 bar, preferably        between 10 bar to 35 bar,    -   hydrogen can be added for controlling the molar mass in a manner        known per se.

The residence time can vary in the three reactor zones.

In one embodiment of the process for producing the heterophasicpropylene copolymer (HECO), the residence time in the first reactor(1^(st) R), i.e. the slurry reactor (SR), like a loop reactor (LR), isin the range 0.2 to 4 hours, e.g. 0.3 to 1.5 hours and the residencetime in the gas phase reactors will generally be 0.2 to 6.0 hours, like0.5 to 4.0 hours.

If desired, the polymerization may be effected in a known manner undersupercritical conditions in the first reactor (1^(st) R), i.e. in theslurry reactor (SR), like in the loop reactor (LR), and/or as acondensed mode in the gas phase reactors (GPR).

Preferably the process comprises also a prepolymerization with thecatalyst system used

In a preferred embodiment, the prepolymerization is conducted as bulkslurry polymerization in liquid propylene, i.e. the liquid phase mainlycomprises propylene, with minor amount of other reactants and optionallyinert components dissolved therein.

The prepolymerization reaction is typically conducted at a temperatureof 0 to 50° C., preferably from 10 to 45° C., and more preferably from15 to 40° C.

The pressure in the prepolymerization reactor is not critical but mustbe sufficiently high to maintain the reaction mixture in liquid phase.Thus, the pressure may be from 20 to 100 bar, for example 30 to 70 bar.

The catalyst components are preferably all introduced to theprepolymerization step. However, where the solid catalyst component (i)and the cocatalyst (ii) can be fed separately it is possible that only apart of the cocatalyst is introduced into the prepolymerization stageand the remaining part into subsequent polymerization stages. Also insuch cases it is necessary to introduce so much cocatalyst into theprepolymerization stage that a sufficient polymerization reaction isobtained therein.

It is possible to add other components also to the prepolymerizationstage. Thus, hydrogen may be added into the prepolymerization stage tocontrol the molecular weight of the prepolymer as is known in the art.Further, antistatic additive may be used to prevent the particles fromadhering to each other or to the walls of the reactor.

The precise control of the prepolymerization conditions and reactionparameters is within the skill of the art.

According to the invention, the heterophasic propylene copolymer (HECO),is obtained by a sequential polymerization process, as described above,in the presence of a catalyst system. It is appreciated that there areno specific restrictions regarding the catalyst system as long as aZiegler-Natta catalyst is used. As regards catalyst systems suitable forpreparing the heterophasic propylene copolymer (HECO), reference is madeto e.g. WO2014/023603, EP591224, WO2012/007430, EP2610271, EP 261027 andEP2610272, which are incorporated herein by reference.

Polyolefin Composition (PO)

It is appreciated that the polyolefin composition (PO) comprises theheterophasic propylene copolymer (HECO) in an amount of ≥95 wt.-%, basedon the total weight of the composition.

In one embodiment of the present invention, the polyolefin composition(PO) comprises the heterophasic propylene copolymer (HECO) in an amountof ≥96 wt.-%, based on the total weight of the composition. Preferably,the polyolefin composition (PO) comprises the heterophasic propylenecopolymer (HECO) in an amount of ≥97 wt.-% or of ≥98 wt.-%, based on thetotal weight of the composition.

For example, the polyolefin composition (PO) comprises the heterophasicpropylene copolymer (HECO) in an amount from 95 to 100 wt.-%, preferablyfrom 96 to 99.8 wt.-%, based on the total weight of the composition.Preferably, the polyolefin composition (PO) comprises the heterophasicpropylene copolymer (HECO) in an amount from 97 to 100 wt.-%, preferablyfrom 97 to 99.8 wt.-%, based on the total weight of the composition.

In one embodiment, the polyolefin composition (PO) consists of theheterophasic propylene copolymer (HECO).

Optionally, the inclusions of the final polyolefin composition (PO) mayalso contain the inorganic filler (F); however, preferably the inorganicfiller (F) forms separate inclusions within the matrix, i.e. thepropylene homopolymer (HPP).

In addition to the polymer components the polyolefin composition (PO)according to the present invention may comprise an inorganic filler (F),preferably in an amount of ≤5 wt.-%, based on the total weight of thecomposition. It is appreciated that the inorganic filler (F) can beselected from the group consisting of talc, wollastonite, mica, chalkand mixtures thereof.

In one embodiment of the present invention, the inorganic filler (F) istalc.

The inorganic filler (F) preferably has an average particle size d₅₀ inthe range of 0.5 to 20.0 μm, more preferably in the range of 0.5 to 15.0μm, still more preferably in the range of 0.75 to 10.0 μm.

Typically, the inorganic filler (F) has a cutoff particle size d₉₅ [masspercent] of equal or below 25.0 μm, more preferably in the range from1.5 to 17.5 μm, still more preferably in the range from 2.0 to 15.0 μm.

The polyolefin composition (PO) has a good flowability, i.e. a ratherlow melt flow rate. It is thus appreciated that the polyolefincomposition (PO) has a melt flow rate MFR₂ (230° C.) measured accordingto ISO 1133 in the range of 15 to 35 g/10 min. More specifically, thepolyolefin composition (PO) has a melt flow rate MFR₂ (230° C.) measuredaccording to ISO 1133 in the range of 18 to 30 g/10 min.

It is further preferred that the polyolefin composition (PO) has anexcellent stiffness/toughness balance. It is thus preferred that thepolyolefin composition (PO) shows good toughness. Accordingly, it isappreciated that the polyolefin composition (PO) has a Charpy notchedimpact strength at +23° C. of ≥30 kJ/m², more preferably in the range of30 to 60 kJ/m², still more preferably in the range of 35 to 60 kJ/m² andmost preferably in the range of 40 to 60 kJ/m².

Additionally or alternatively, the polyolefin composition (PO) has aCharpy notched impact strength at −20° C. of ≥8 kJ/m², more preferablyin the range of 8 to 14 kJ/m², still more preferably in the range of 9to 14 kJ/m² and most preferably in the range of 9 to 13 kJ/m².

Additionally or alternatively, the polyolefin composition (PO) shouldhave good tensile modulus. It is preferred that the tensile modulus ofthe polyolefin composition (PO) is ≥750 MPa, more preferably in therange of 750 to 1050 MPa, even more preferably of 800 to 1000 MPa, stillmore preferably in the range of 800 to 980 MPa and most preferably inthe range of 800 to 950 MPa.

Thus, the polyolefin composition (PO) preferably has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, preferably in the range of 18 to 30    g/10 min, and-   ii) a tensile modulus of ≥750 MPa, more preferably in the range of    750 to 1050 MPa, even more preferably of 800 to 1000 MPa, still more    preferably in the range of 800 to 980 MPa and most preferably in the    range of 800 to 950 MPa, and/or-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², more    preferably in the range of 30 to 60 kJ/m², still more preferably in    the range of 35 to 60 kJ/m² and most preferably in the range of 40    to 60 kJ/m², and/or-   iv) a Charpy notched impact strength at −20° C. of ≥8 kJ/m², more    preferably in the range of 8 to 14 kJ/m², still more preferably in    the range of 9 to 14 kJ/m² and most preferably in the range of 9 to    13 kJ/m².

In one embodiment, the polyolefin composition (PO) has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, preferably in the range of 18 to 30    g/10 min, and-   ii) a tensile modulus of ≥750 MPa, more preferably in the range of    750 to 1050 MPa, even more preferably of 800 to 1000 MPa, still more    preferably in the range of 800 to 980 MPa and most preferably in the    range of 800 to 950 MPa, and-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², more    preferably in the range of 30 to 60 kJ/m², still more preferably in    the range of 35 to 60 kJ/m² and most preferably in the range of 40    to 60 kJ/m², or-   iv) a Charpy notched impact strength at −20° C. of ≥8 kJ/m², more    preferably in the range of 8 to 14 kJ/m², still more preferably in    the range of 9 to 14 kJ/m² and most preferably in the range of 9 to    13 kJ/m².

Alternatively, the polyolefin composition (PO) has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, preferably in the range of 18 to 30    g/10 min, and-   ii) a tensile modulus of ≥750 MPa, more preferably in the range of    750 to 1050 MPa, even more preferably of 800 to 1000 MPa, still more    preferably in the range of 800 to 980 MPa and most preferably in the    range of 800 to 950 MPa, and-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², more    preferably in the range of 30 to 60 kJ/m², still more preferably in    the range of 35 to 60 kJ/m² and most preferably in the range of 40    to 60 kJ/m², and-   iv) a Charpy notched impact strength at −20° C. of ≥8 kJ/m², more    preferably in the range of 8 to 14 kJ/m², still more preferably in    the range of 9 to 14 kJ/m² and most preferably in the range of 9 to    13 kJ/m².

Alternatively, the polyolefin composition (PO) has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, preferably in the range of 18 to 30    g/10 min, and-   ii) a tensile modulus of ≥750 MPa, more preferably in the range of    750 to 1050 MPa, even more preferably of 800 to 1000 MPa, still more    preferably in the range of 800 to 980 MPa and most preferably in the    range of 800 to 950 MPa, or-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², more    preferably in the range of 30 to 60 kJ/m², still more preferably in    the range of 35 to 60 kJ/m² and most preferably in the range of 40    to 60 kJ/m², and-   iv) a Charpy notched impact strength at −20° C. of ≥8 kJ/m², more    preferably in the range of 8 to 14 kJ/m², still more preferably in    the range of 9 to 14 kJ/m² and most preferably in the range of 9 to    13 kJ/m².

Preferably, the polyolefin composition (PO) has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, preferably in the range of 18 to 30    g/10 min, and-   ii) a tensile modulus of ≥750 MPa, more preferably in the range of    750 to 1050 MPa, even more preferably of 800 to 1000 MPa, still more    preferably in the range of 800 to 980 MPa and most preferably in the    range of 800 to 950 MPa, and-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², more    preferably in the range of 30 to 60 kJ/m², still more preferably in    the range of 35 to 60 kJ/m² and most preferably in the range of 40    to 60 kJ/m², and-   iv) a Charpy notched impact strength at −20° C. in the range of 5 to    20 kJ/m², still more preferably in the range of 5 to 16 kJ/m² and    most preferably in the range of 6 to 13 kJ/m².

For preparing the polyolefin composition (PO), a conventionalcompounding or blending apparatus, e.g. a Banbury mixer, a 2-roll rubbermill, Buss-co-kneader or a twin screw extruder may be used. Thepolyolefin composition (PO) recovered from the extruder is usually inthe form of pellets. These pellets are then preferably furtherprocessed, e.g. by injection moulding to generate articles and productsof the inventive polyolefin composition (PO).

Accordingly the present invention is also directed to a process for thepreparation of the polyolefin composition (PO) comprising the steps ofadding the heterophasic propylene copolymer (HECO) and optionally theinorganic filler (F) to an extruder (as mentioned above) and extrudingthe same obtaining thereby said polyolefin composition (PO).

It is preferred that the heterophasic propylene copolymer (HECO) isobtained by producing the propylene homopolymer (HPP) in at least onereactor, e.g. two reactors, transferring said propylene homopolymer(HPP) in at least one subsequent reactor, e.g. two reactors, where inthe presence of the propylene homopolymer (HPP) the elastomericpropylene-ethylene copolymer (E) is produced.

The polyolefin composition (PO) according to the invention may bepelletized and compounded using any of the variety of compounding andblending methods well known and commonly used in the resin compoundingart.

Automotive Articles and Uses According to the Invention

It is appreciated that the instant heterophasic propylene copolymer(HECO) provides a combination of good flowability with an excellentstiffness/toughness balance below ambient temperature, preferably topolyolefin compositions prepared therefrom.

Accordingly, it is to be noted that molded articles prepared from theheterophasic propylene copolymer (HECO) and/or the polyolefincomposition (PO) show a good flowability with an excellentstiffness/toughness balance below ambient temperature.

Thus, according to another aspect of the present invention, the use ofthe heterophasic propylene copolymer (HECO), as defined herein, forimproving the mechanical properties of a polyolefin composition (PO) isprovided, wherein the improvement is achieved when the polyolefincomposition (PO) has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, and-   ii) a tensile modulus of ≥750 MPa, and/or-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², and/or-   iv) a Charpy Notched impact strength at −20° C. of ≥8 kJ/m².

In one embodiment, the improvement is achieved when the polyolefincomposition (PO) has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, and-   ii) a tensile modulus of ≥750 MPa, and-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², or-   iv) a Charpy Notched impact strength at −20° C. of ≥8 kJ/m².

Preferably, the improvement is achieved when the polyolefin composition(PO) has

-   i) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 15 to 35 g/10 min, and-   ii) a tensile modulus of ≥750 MPa, and-   iii) a Charpy Notched impact strength at 23° C. of ≥30 kJ/m², and-   iv) a Charpy Notched impact strength at −20° C. of ≥8 kJ/m².

With regard to the definition of the heterophasic propylene copolymer(HECO), the polyolefin composition (PO) and preferred embodimentsthereof, reference is made to the statements provided above whendiscussing the technical details of the heterophasic propylene copolymer(HECO) and the polyolefin composition (PO).

The heterophasic propylene copolymer (HECO) and/or the polyolefincomposition (PO) is/are preferably part of an automotive article,preferably a (injection) molded automotive article, i.e. of (interior orexterior) automotive article. For example, the heterophasic propylenecopolymer (HECO) and/or the polyolefin composition (PO) is/are part of acomposition, which is in turn part of the automotive article, preferably(injection) molded automotive article, i.e. of (interior or exterior)automotive article.

It is especially preferred that the heterophasic propylene copolymer(HECO) is part of the polyolefin composition (PO), which is in turn partof the automotive article, preferably (injection) molded automotivearticle, i.e. of (interior or exterior) automotive article.

In view of the very good results obtained, the present invention is notonly directed to the heterophasic propylene copolymer (HECO) and/or thepolyolefin composition (PO), but also to an automotive article in whichthe heterophasic propylene copolymer (HECO) and/or the polyolefincomposition (PO) is part of it.

Accordingly the present invention is additionally directed to anautomotive article, comprising the heterophasic propylene copolymer(HECO) and/or the polyolefin composition (PO).

Preferably, the automotive article comprises the polyolefin composition(PO), said polyolefin composition (PO) comprises, preferably consistsof, the heterophasic propylene copolymer (HECO) comprising

-   a) a propylene homopolymer (HPP) having a melt flow rate MFR₂ (230°    C.) measured according to ISO 1133 in the range of 200 to 350 g/10    min, and-   b) an elastomeric propylene-ethylene copolymer (E),-   wherein the heterophasic propylene copolymer (HECO)-   (i) has a melt flow rate MFR₂ (230° C.) measured according to ISO    1133 in the range of 15 to 35 g/10 min,-   (ii) comprises a xylene cold soluble (XCS) fraction in an amount    from 34 to 40 wt.-%, based on the total weight of the heterophasic    propylene copolymer (HECO),-   wherein further the xylene cold soluble (XCS) fraction of the    heterophasic propylene copolymer (HECO) has-   (iii) an intrinsic viscosity (IV) in the range of 2.8 to 3.8 dl/g,    and-   (iv) an ethylene content (EC) of 25 to 35 wt.-% based on the total    weight of the xylene cold soluble (XCS) fraction of the heterophasic    propylene copolymer (HECO).

The term “automotive article” used in the instant invention indicatesthat it is a formed three-dimensional article for the interior orexterior of automotives. Typical automotive articles are bumpers, bodypanels, rocker panels, side trim panels, interior trims, step assists,spoilers, fenders, dash boards and the like. The term “exterior”indicates that the article is not part of the car interior but part ofthe car's exterior. Accordingly, preferred exterior automotive articlesare selected from the group consisting of bumpers, side trim panels,step assists, body panels, fenders and spoilers. In contrast thereto,the term “interior” indicates that the article is part of the carinterior but not part of the car's exterior. Accordingly, preferredinterior automotive articles are selected from the group consisting ofrocker panels, dash boards and interior trims.

Preferably the automotive article, i.e. the exterior or interiorautomotive article, comprises equal or more than 50.0 wt.-%, morepreferably equal or more than 55.0 wt.-%, yet more preferably equal ormore than 70.0 wt.-%, still more preferably equal or more than 80.0wt.-%, still yet more preferably consists, of the heterophasic propylenecopolymer (HECO) and/or the polyolefin composition (PO).

In one embodiment, the automotive article, i.e. the exterior or interiorautomotive article, comprises equal or more than 80.0 wt.-%, morepreferably equal or more than 90.0 wt.-%, yet more preferably equal ormore than 95.0 wt.-%, still more preferably equal or more than 99.0wt.-%, still yet more preferably consists of the heterophasic propylenecopolymer (HECO) and/or the polyolefin composition (PO).

For mixing the individual components of the instant polyolefincomposition (PO), a conventional compounding or blending apparatus, e.g.a Banbury mixer, a 2-roll rubber mill, Buss-co-kneader or a twin screwextruder may be used. The polymer materials recovered from the extruderare usually in the form of pellets. These pellets are then preferablyfurther processed, e.g. by injection molding to generate the articles,i.e. the (interior or exterior) automotive articles.

The present invention will now be described in further detail by theexamples provided below.

EXAMPLES

A. Measuring Methods

The following definitions of terms and determination methods apply forthe above general description of the invention as well as to the belowexamples unless otherwise defined. Calculation of comonomer content ofthe second fraction (F2):

$\frac{{C\left( {R\; 2} \right)} - {{w\left( {F\; 1} \right)}x\mspace{14mu} {C\left( {F\; 1} \right)}}}{w\left( {F\; 2} \right)} = {C\left( {F\; 2} \right)}$

-   wherein-   w(F1) is the weight fraction of the first fraction (F1), i.e. the    product of the first reactor (R1),-   w(F2) is the weight fraction of the second fraction (F2), i.e. of    the polymer produced in the second reactor (R2),-   C(F1) is the comonomer content [in wt.-%] of the first fraction    (F1), i.e. of the product of the first reactor (R1),-   C(R2) is the comonomer content [in wt.-%] of the product obtained in    the second reactor (R2), i.e. the mixture of the first fraction (F1)    and the second fraction (F2),-   C(F2) is the calculated comonomer content [in wt.-%] of the second    fraction (F2).

Calculation of the xylene cold soluble (XCS) content of the secondfraction (F2):

$\frac{{{XS}\left( {R\; 2} \right)} - {{w\left( {F\; 1} \right)}x\mspace{14mu} {{XS}\left( {F\; 1} \right)}}}{w\left( {F\; 2} \right)} = {{XS}\left( {F\; 2} \right)}$

-   wherein-   w(F1) is the weight fraction of the first fraction (1), i.e. the    product of the first reactor (R1),-   w(F2) is the weight fraction of the second fraction (F2), i.e. of    the polymer produced in the second reactor (R2),-   XS(F1) is the xylene cold soluble (XCS) content [in wt.-%] of the    first fraction (F1), i.e. of the product of the first reactor (R1),-   XS(R2) is the xylene cold soluble (XCS) content [in wt.-%] of the    product obtained in the second reactor (R2), i.e. the mixture of the    first fraction (F1) and the second fraction (F2),-   XS(F2) is the calculated xylene cold soluble (XCS) content [in    wt.-%] of the second fraction (F2).

Calculation of melt flow rate MFR₂ (230° C.) of the second fraction(F2):

${{MFR}\left( {F\; 2} \right)} = 10^{\lbrack\frac{{\log {({{MFR}{({R\; 2})}})}} - {{w{({F\; 1})}} \times {\log {({{MFR}{({F\; 1})}})}}}}{w{({F\; 2})}}\rbrack}$

-   wherein-   w(F1) is the weight fraction of the first fraction (F1), i.e. the    product of the first reactor (R1),-   w(F2) is the weight fraction of the second fraction (F2), i.e. of    the polymer produced in the second reactor (R2),-   MFR(F1) is the melt flow rate MFR₂ (230° C.) [in g/10 min] of the    first fraction (F1), i.e. of the product of the first reactor (R1),-   MFR(R2) is the melt flow rate MFR₂ (230° C.) [in g/10 min] of the    product obtained in the second reactor (R2), i.e. the mixture of the    first fraction (F1) and the second fraction (F2),-   MFR(F2) is the calculated melt flow rate MFR₂ (230° C.) [in g/10    min] of the second fraction (F2).

Calculation of comonomer content of the third fraction (F3):

$\frac{{C\left( {R\; 3} \right)} - {{w\left( {R\; 2} \right)}x\mspace{14mu} {C\left( {R\; 2} \right)}}}{w\left( {F\; 3} \right)} = {C\left( {F\; 3} \right)}$

-   wherein-   w(R2) is the weight fraction of the second reactor (R2), i.e. the    mixture of the first fraction (1) and the second fraction (F2),-   w(F3) is the weight fraction of the third fraction (F3), i.e. of the    polymer produced in the third reactor (R3),-   C(R2) is the comonomer content [in wt.-%] of the product of the    second reactor (R2), i.e. of the mixture of the first fraction (F1)    and second fraction (F2),-   C(R3) is the comonomer content [in wt.-%] of the product obtained in    the third reactor (R3), i.e. the mixture of the first fraction (F1),    the second fraction (F2), and the third fraction (F3),-   C(F3) is the calculated comonomer content [in wt.-%] of the third    fraction (F3).

Calculation of xylene cold soluble (XCS) content of the third fraction(F3):

$\frac{{{XS}\left( {R\; 3} \right)} - {{w\left( {R\; 2} \right)}x\mspace{14mu} {{XS}\left( {R\; 2} \right)}}}{w\left( {F\; 3} \right)} = {{XS}\left( {F\; 3} \right)}$

-   wherein-   w(R2) is the weight fraction of the second reactor (R2), i.e. the    mixture of the first fraction (F1) and the second fraction (F2),-   w(F3) is the weight fraction of the third fraction (F3), i.e. of the    polymer produced in the third reactor (R3),-   XS(R2) is the xylene cold soluble (XCS) content [in wt.-%] of the    product of the second reactor (R2), i.e. of the mixture of the first    fraction (F1) and second fraction (F2),-   XS(R3) is the xylene cold soluble (XCS) content [in wt.-%] of the    product obtained in the third reactor (R3), i.e. the mixture of the    first fraction (F1), the second fraction (F2), and the third    fraction (F3),-   XS(F3) is the calculated xylene cold soluble (XCS) content [in    wt.-%] of the third fraction (F3).

Calculation of melt flow rate MFR₂ (230° C.) of the third fraction (F3):

${{MFR}\left( {F\; 3} \right)} = 10^{\lbrack\frac{{\log {({{MFR}{({R\; 3})}})}} - {{w{({R\; 2})}} \times {\log {({{MFR}{({R\; 2})}})}}}}{w{({F\; 3})}}\rbrack}$

-   wherein-   w(R2) is the weight fraction of the second reactor (R2), i.e. the    mixture of the first fraction (F1) and the second fraction (F2),-   w(F3) is the weight fraction of the third fraction (F3), i.e. of the    polymer produced in the third reactor (R3),-   MFR(R2) is the melt flow rate MFR₂ (230° C.) [in g/10 min] of the    product of the second reactor (R2), i.e. of the mixture of the first    fraction (F1) and second fraction (F2),-   MFR(R3) is the melt flow rate MFR₂ (230° C.) [in g/10 min] of the    product obtained in the third reactor (R3), i.e. the mixture of the    first fraction (F1), the second fraction (F2), and the third    fraction (F3),-   MFR(F3) is the calculated melt flow rate MFR₂ (230° C.) [in g/10    min] of the third fraction (F3).

Calculation of comonomer content of the fourth fraction (F41:

$\frac{{C\left( {R\; 4} \right)} - {{w\left( {R\; 3} \right)}x\mspace{14mu} {C\left( {R\; 3} \right)}}}{w\left( {F\; 4} \right)} = {C\left( {F\; 4} \right)}$

-   wherein-   w(R3) is the weight fraction of the third reactor (R3), i.e. the    mixture of the first fraction (F1), the second fraction (F2) and the    fourth fraction (F3),-   w(F4) is the weight fraction of the fourth fraction (F4), i.e. of    the polymer produced in the fourth reactor (R4),-   C(R3) is the comonomer content [in wt.-%] of the product of the    third reactor (R3), i.e. of the mixture of the first fraction (F1),    the second fraction (F2) and the third fraction (F3),-   C(R4) is the comonomer content [in wt.-%] of the product obtained in    the fourth reactor (R4), i.e. the mixture of the first fraction    (F1), the second fraction (F2), the third fraction (F3) and the    fourth fraction (F4),-   C(F4) is the calculated comonomer content [in wt.-%] of the fourth    fraction (F4).

Calculation of xylene cold soluble (XCS) content of the fourth fraction(F4):

$\frac{{{XS}\left( {R\; 4} \right)} - {{w\left( {R\; 3} \right)}x\mspace{14mu} {{XS}\left( {R\; 3} \right)}}}{w\left( {F\; 4} \right)} = {{XS}\left( {F\; 4} \right)}$

-   wherein-   w(R3) is the weight fraction of the third reactor (R3), i.e. the    mixture of the first fraction (F1), the second fraction (F2) an the    third fraction (F3),-   w(F4) is the weight fraction of the fourth fraction (F4), i.e. of    the polymer produced in the fourth reactor (R4),-   XS(R3) is the xylene cold soluble (XCS) content [in wt.-%] of the    product of the third reactor (R3), i.e. of the mixture of the first    fraction (F1), the second fraction (F2) and the third fraction (F3),-   XS(R4) is the xylene cold soluble (XCS) content [in wt.-%] of the    product obtained in the fourth reactor (R4), i.e. the mixture of the    first fraction (F1), the second fraction (F2), the third fraction    (F3) and the fourth fraction,-   XS(F4) is the calculated xylene cold soluble (XCS) content [in    wt.-%] of the fourth fraction (F4).

Calculation of melt flow rate MFR₂ (230° C.) of the fourth fraction(F4):

${{MFR}\left( {F\; 4} \right)} = 10^{\lbrack\frac{{\log {({{MFR}{({R\; 4})}})}} - {{w{({R\; 3})}} \times {\log {({{MFR}{({R\; 3})}})}}}}{w{({F\; 4})}}\rbrack}$

-   wherein-   w(R3) is the weight fraction of the third reactor (R3), i.e. the    mixture of the first fraction (F1), the second fraction (F2) an the    third fraction (F3),-   w(F4) is the weight fraction of the fourth fraction (F4), i.e. of    the polymer produced in the fourth reactor (R4),-   MFR(R3) is the melt flow rate MFR₂ (230° C.) [in g/10 min] of the    product of the third reactor (R3), i.e. of the mixture of the first    fraction (F1), the second fraction (F2) and the third fraction (F3),-   MFR(R4) is the melt flow rate MFR₂ (230° C.) [in g/10 min] of the    product obtained in the fourth reactor (R4), i.e. the mixture of the    first fraction (F1), the second fraction (F2), the third fraction    (F3) and the fourth fraction (F4),-   MFR(F4) is the calculated melt flow rate MFR₂ (230° C.) [in g/10    min] of the fourth fraction (F4).

NMR-Spectroscopy Measurements:

The ¹³C-NMR spectra of polypropylenes were recorded on Bruker 400 MHzspectrometer at 130° C. from samples dissolved in1,2,4-trichlorobenzene/benzene-d₆ (90/10 w/w). For the pentad analysisthe assignment is done according to the methods described in literature:(T. Hayashi, Y. Inoue, R. Chüjö, and T. Asakura, Polymer 29 138-43(1988). and Chujo R, et al, Polymer 35 339 (1994).

The NMR-measurement was used for determining the mmmm pentadconcentration in a manner well known in the art.

Quantification of Comonomer Content by FTIR Spectroscopy

The comonomer content is determined by quantitative Fourier transforminfrared spectroscopy (FTIR) after basic assignment calibrated viaquantitative ¹³C nuclear magnetic resonance (NMR) spectroscopy in amanner well known in the art. Thin films are pressed to a thickness ofbetween 100-500 μm and spectra recorded in transmission mode.Specifically, the ethylene content of a polypropylene-co-ethylenecopolymer is determined using the baseline corrected peak area of thequantitative bands found at 720-722 and 730-733 cm⁻¹. Specifically, thebutene or hexene content of a polyethylene copolymer is determined usingthe baseline corrected peak area of the quantitative bands found at1377-1379 cm⁻¹. Quantitative results are obtained based upon referenceto the film thickness.

Density is measured according to ISO 1183-187. Sample preparation isdone by compression moulding in accordance with ISO 1872-2:2007.

MFR₂ (230° C.) is measured according to ISO 1133 (230° C., 2.16 kgload).

MFR₂ (190° C.) is measured according to ISO 1133 (190° C., 2.16 kgload).

Intrinsic viscosity is measured according to DIN ISO 1628/1, October1999 (in Decalin at 135° C.).

Xylene cold soluble fraction (XCS wt.-%): Content of xylene coldsolubles (XCS) is determined at 25° C. according ISO 16152; firstedition; 2005 Jul. 1. The part which remains insoluble is the xylenecold insoluble (XCI) fraction.

-   Melting temperature T_(m), crystallization temperature T_(c), is    measured with Mettler TA820 differential scanning calorimetry (DSC)    on 5-10 mg samples. Both crystallization and melting curves were    obtained during 10° C./min cooling and heating scans between 30° C.    and 225° C. Melting and crystallization temperatures were taken as    the peaks of endotherms and exotherms.

Also the melt- and crystallization enthalpy (Hm and Hc) were measured bythe DSC method according to ISO 11357-1.

Number average molecular weight (Me), weight average molecular weight(Mw) and molecular weight distribution (MWD) are determined by GelPermeation Chromatography (GPC) according to the following method:

The weight average molecular weight Mw and the molecular weightdistribution (MWD=Mw/Mn wherein Mn is the number average molecularweight and Mw is the weight average molecular weight) is measured by amethod based on ISO 16014-1:2003 and ISO 16014-4:2003. A Waters AllianceGPCV 2000 instrument, equipped with refractive index detector and onlineviscosimeter was used with 3×TSK-gel columns (GMHXL-HT) from TosoHaasand 1,2,4-trichlorobenzene (TCB, stabilized with 200 mg/L 2,6-Di tertbutyl-4-methyl-phenol) as solvent at 145° C. and at a constant flow rateof 1 mL/min. 216.5 μL of sample solution were injected per analysis. Thecolumn set was calibrated using relative calibration with 19 narrow MWDpolystyrene (PS) standards in the range of 0.5 kg/mol to 11 500 kg/moland a set of well characterized broad polypropylene standards. Allsamples were prepared by dissolving 5-10 mg of polymer in 10 mL (at 160°C.) of stabilized TCB (same as mobile phase) and keeping for 3 hourswith continuous shaking prior sampling in into the GPC instrument.

Median particle size d₅₀ (Sedimentation) is calculated from the particlesize distribution [mass percent] as determined by gravitational liquidsedimentation according to ISO 13317-3 (Sedigraph).

Tensile Modulus; Tensile strain at break were measured according to ISO527-2 (cross head speed=50 mm/min; 23° C.) using injection moldedspecimens as described in EN ISO 1873-2 (dog bone shape, 4 mmthickness).

Flexural modulus was measured according to ISO 178 using injectionmolded test specimen as described in EN ISO 1873-2 with dimensions of80×10×4 mm³. Crosshead speed was 2 mm/min for determining the flexuralmodulus.

Charpy impact test: The Charpy notched impact strength (Charpy NIS) ismeasured according to ISO 179-1/1eA/DIN 53453 at 23° C., −20° C. and−30° C., using injection molded bar test specimens of 80×10×4 mm³ mm³prepared in accordance with ISO 294-1:1996.

Shrinkage (SH) radial; Shrinkage (SH) tangential were determined oncentre gated, injection moulded circular disks (diameter 180 mm,thickness 3 mm, having a flow angle of 355° and a cut out of 5°). Twospecimens are moulded applying two different holding pressure times (10s and 20 s respectively). The melt temperature at the gate is 260° C.,and the average flow front velocity in the mould 100 mm/s. Tooltemperature: 40° C., back pressure: 600 bar.

After conditioning the specimen at room temperature for 96 hours thedimensional changes radial and tangential to the flow direction aremeasured for both disks. The average of respective values from bothdisks are reported as final results.

Cutoff particle size d₉₅ (Sedimentation) is calculated from the particlesize distribution [mass percent] as determined by gravitational liquidsedimentation according to ISO 13317-3 (Sedigraph).

2. Examples

All polymers were produced in a Borstar pilot plant with aprepolymerization reactor, one slurry loop reactor and three gas phasereactors. The catalyst used in the polymerization process for theinventive example was the commercially available BCF55P catalyst (1.8wt.-% Ti-Ziegler-Natta-catalyst as described in EP 591 224) of BorealisAG with triethylaluminium (TEAL) as cocatalyst anddiethylaminotriethoxysilane [Si(OCH₂CH₃)₃(N(CH₂CH₃)₂)] (U donor) ordicyclo pentyl dimethoxy silane (D-donor). The preparation of theheterophasic propylene copolymer (HECO) comprising the propylenehomopolymer (HPP) and the elastomeric propylene-ethylene copolymer (E)including the aluminium to donor ratio is described in the followingTable 1. Table 1 also outlines the preparation conditions for thecomparative examples (CE).

Table 2 summarizes the property profiles of the inventive heterophasicpropylene copolymers (HECO) and the comparative examples (CE).

TABLE 1 Polymerization conditions of the inventive heterophasicpropylene copolymers (HECO) and comparative examples (CE) HECO1 HECO2HECO3 CE1 CE2 CE3 CE4 CE5 CE6 Donor U U U D U D D U D TEAL/D [mol/mol] 55 8 13 11 13 13 5 13 Matrix split [wt.-%] 64 65 62 67 66 66 64 65 61MFR₂ [g/10 min] 256 257 300 77 185 186 189 283 63 E Split [wt.-%] 36 3538 33 34 34 36 35 39 H2/C3 ratio [mol/kmol] 74 74 50 140 90 130/160*130/160* 80 140 C2/C3 ratio [mol/kmol] 230 230 235 555 460 300 300256/225* 555 *bimodal

TABLE 2 Properties of the heterophasic propylene copolymers (HECO) andthe comparative examples (CE) Example HECO1 HECO2 HECO3 CE1 CE2 CE3 CE4CE5 CE6 Matrix [wt.-%] 63.9 65.3 63.0 72.5 70.7 70.0 68.7 70.2 65.0 MFR₂Matrix [g/10 min] 256 258 300 77   185   186   189   283   63   XCS[wt.-%] 36.1 34.7 37.0 27.5 29.3 30.0 31.3 29.8 35.0 IV (XCS) [dl/g] 2.92.9 3.6  3.3  3.1  3.5  3.5  3.3  3.1 C2 (XCS) [wt %] 32.2 32.2 32.040.6 42.7 30   30   31.0 40.0 MFR_(2total) [g/10 min] 27.1 28.1 21.020.5 44.8 26.6 21.3 27.6 13   C2 total [wt %] 15.3 14.9 16 11^(# )13^(# )  9^(#)  9^(#)  9^(#) 15^(# ) Tensile [MPa] 885 911 826 1203   1090    1046    990   1008    856   modulus Tensile strain [%] 40 35 3846   24   179   336   109   221   at break Flexural [MPa] nd nd 770.61018    920   869   824   nd nd modulus Charpy NIS [kJ/m²] 52.5 54.042.5 16.2 29.4 57.2 60.9 50.8 68.7 +23° C. Charpy NIS −20° C. [kJ/m²]10.1 9.8 11.4  6.8  7.2  5.4  6.0  6.5 13.5 SH radial [%] 1.77 1.65 1.67 1.65  1.68  1.62  1.60  1.70  1.55 SH tangential [%] 1.45 1.51 1.58 1.52  1.53  1.46  1.43  1.56  1.33 nd: not determined ^(#)values werecalculated

In contrast to the comparative examples, the inventive materials HECO1,HECO2 and HECO3 provide an excellent combination of mechanicalproperties. In particular, it can be gathered that the inventiveheterophasic propylene copolymers (HECO) provide good flowability incombination with an excellent stiffness/toughness balance below ambienttemperature.

1. A heterophasic propylene copolymer (HECO) comprising a) a propylenehomopolymer (HPP) having a melt flow rate MFR₂ (230° C.) measuredaccording to ISO 1133 in the range of 200 to 350 g/10 min, and b) anelastomeric propylene-ethylene copolymer (E), wherein the heterophasicpropylene copolymer (HECO) (i) has a melt flow rate MFR₂ (230° C.)measured according to ISO 1133 in the range of 15 to 35 g/10 min, (ii)comprises a xylene cold soluble (XCS) fraction in an amount from 34 to40 wt.-%, based on the total weight of the heterophasic propylenecopolymer (HECO), wherein further the xylene cold soluble (XCS) fractionof the heterophasic propylene copolymer (HECO) has (iii) an intrinsicviscosity (IV) in the range of 2.8 to 3.8 dl/g measured according to DINISO 1628/1, and (iv) an ethylene content (EC) of 25 to 35 wt.-%, basedon the total weight of the xylene cold soluble (XCS) fraction of theheterophasic propylene copolymer (HECO).
 2. The heterophasic propylenecopolymer (HECO) according to claim 1, wherein the propylene homopolymer(HPP) is unimodal with respect to the melt flow rate MFR₂ (230° C.)measured according to ISO 1133, has a xylene cold soluble (XCS) contentno higher than 5 wt.-%, or is unimodal with respect to the melt flowrate MFR₂ (230° C.) measured according to ISO 1133 and has a xylene coldsoluble (XCS) content of no higher than 5 wt.-%.
 3. The heterophasicpropylene copolymer (HECO) according to claim 1, wherein theheterophasic propylene copolymer (HECO) has an ethylene content(EC-HECO) of 8 to 17 wt.-%, based on the total weight of theheterophasic propylene copolymer (HECO).
 4. The heterophasic propylenecopolymer (HECO) according to claim 1, wherein the xylene cold soluble(XCS) fraction is unimodal with respect to the ethylene content (EC),unimodal with respect to a molecular weight distribution (MWD), orunimodal with respect to the ethylene content (EC) and with respect tothe molecular weight distribution (MWD).
 5. The heterophasic propylenecopolymer (HECO) according to claim 1, wherein the weight ratio ofheterophasic propylene copolymer (HECO) to the polypropylene homopolymer(HPP) [HECO/HPP] is from 3.0:1.0 to 1.0:1.0.
 6. The heterophasicpropylene copolymer (HECO) according to claim 1, wherein theheterophasic propylene copolymer (HECO) is α-nucleated.
 7. A polyolefincomposition (PO) comprising ≥95 wt.-%, based on the total weight of thecomposition, of the heterophasic propylene copolymer (HECO) according toclaim
 1. 8. The polyolefin composition (PO) according to claim 7,wherein the composition comprises an inorganic filler (F).
 9. Thepolyolefin composition (PO) according to claim 7, wherein thecomposition has i) a melt flow rate MFR₂ (230° C.) measured according toISO 1133 in the range of 15 to 35 g/10 min, and one or more of: ii) atensile modulus of ≥750 MPa measured according to ISO 527-2, or iii) aCharpy Notched impact strength at 23° C. of ≥30 kJ/m2 measured accordingto ISO 179-1/1eA, or iv) a Charpy Notched impact strength at −20° C. of≥8 kJ/m2 measured according to ISO 179-1/1eA.
 10. The polyolefincomposition (PO) according to claim 9, wherein the composition has oneor more of: i) a tensile modulus in the range of 750 to 1050 MPameasured according to ISO 527-2, or ii) a Charpy Notched impact strengthat 23° C. in the range of 30 to 60 kJ/m2 measured according to ISO179-1/1eA, or iii) a Charpy Notched impact strength at −20° C. in therange of 8 to 14 kJ/m2 measured according to ISO 179-1/1eA.
 11. Anautomotive article comprising at least one of a heterophasic propylenecopolymer (HECO) a polyolefin composition (PO), wherein the heterophasicpropylene copolymer (HECO) comprises a) a propylene homopolymer (HPP)having a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 inthe range of 200 to 350 g/10 min, and b) an elastomericpropylene-ethylene copolymer (E), wherein the heterophasic propylenecopolymer (HECO) (i) has a melt flow rate MFR₂ (230° C.) measuredaccording to ISO 1133 in the range of 15 to 35 g/10 min, (ii) comprisesa xylene cold soluble (XCS) fraction in an amount from 34 to 40 wt.-%,based on the total weight of the heterophasic propylene copolymer(HECO), wherein further the xylene cold soluble (XCS) fraction of theheterophasic propylene copolymer (HECO) has (iii) an intrinsic viscosity(IV) in the range of 2.8 to 3.8 dl/g measured according to DIN ISO1628/1, and (iv) an ethylene content (EC) of 25 to 35 wt.-%, based onthe total weight of the xylene cold soluble (XCS) fraction of theheterophasic propylene copolymer (HECO); and wherein the polyolefincomposition (PO) comprises ≥95 wt.-%, based on the total weight of thepolyolefin composition, of the heterophasic propylene copolymer (HECO).12. The automotive article according to claim 11, wherein the automotivearticle is an exterior or interior automotive article selected frombumpers, body panels, rocker panels, side trim panels, interior trims,step assists, spoilers, fenders and dash boards.
 13. A process for thepreparation of a polyolefin composition (PO) according to claim 8, theprocess comprising extruding the heterophasic propylene copolymer (HECO)and the optional inorganic filler (F) in an extruder.
 14. The processaccording to claim 13, wherein the heterophasic propylene copolymer(HECO) is obtained by producing the propylene homopolymer (HPP) in atleast one reactor, transferring said propylene homopolymer (HPP) in atleast one subsequent reactor, and producing the elastomericpropylene-ethylene copolymer (E) in the presence of the propylenehomopolymer (HPP).
 15. A method comprising improving the mechanicalproperties of a polyolefin composition (PO) with the heterophasicpropylene copolymer (HECO) according to claim 1, wherein the improvementis achieved when the composition has i) a melt flow rate MFR₂ (230° C.)measured according to ISO 1133 in the range of 15 to 35 g/10 min, andone or more of ii) a tensile modulus of ≥750 MPa measured according toISO 527-2, or iii) a Charpy Notched impact strength at 23° C. of ≥30kJ/m2 measured according to ISO 179-1/1eA, or iv) a C
 16. Theheterophasic propylene copolymer (HECO) according to claim 6, whereinthe heterophasic propylene copolymer (HECO) comprises a α-nucleatingagent.
 17. The polyolefin composition (PO) according to claim 8, whereinthe inorganic filler (F) is selected from the group consisting of talc,wollastonite, mica, chalk and mixtures thereof.
 18. The polyolefincomposition (PO) according to claim 8, wherein the composition has i) amelt flow rate MFR₂ (230° C.) measured according to ISO 1133 in therange of 15 to 35 g/10 min, and one or more of: ii) a tensile modulus of≥750 MPa measured according to ISO 527-2, or iii) a Charpy Notchedimpact strength at 23° C. of ≥30 kJ/m2 measured according to ISO179-1/1eA, or iv) a Charpy Notched impact strength at −20° C. of ≥8kJ/m2 measured according to ISO 179-1/1eA.
 19. The polyolefincomposition (PO) according to claim 18, wherein the composition has oneor more of: i) a tensile modulus in the range of 750 to 1050 MPameasured according to ISO 527-2, or ii) a Charpy Notched impact strengthat 23° C. in the range of 30 to 60 kJ/m2 measured according to ISO179-1/1eA, or iii) a Charpy Notched impact strength at −20° C. in therange of 8 to 14 kJ/m2 measured according to ISO 179-1/1eA.